Fig . Iron chain left in moist air got rusted
Corrosion causes damage to car bodies , bridges , iron railings , ships and to all objects made of metals , especially those of iron .
o In case of rusting of copper , the metallic copper reacts with oxygen , carbon-dioxide and atmospheric moisture and develops a green coloured coating of copper hydroxide and copper carbonate .
Fig . Copper developing green coloured rust on exposure to moist air o
In case of tarnishing of silver articles , the metallic silver reacts with hydrogen sulphide or sulphur present in air and gets tarnished .
Fig . Tarnished silver Vs polished silver